Alkyl glycosides and their applications are known in particular from the documents US 2006/0046969 and WO 2006/107386.
Patent application WO 2005/041983 discloses the use, as novel medicament advantageously intended for regulating inflammatory mechanisms, of a reducing alkylsugar monomer whose hydroxyl functional group is substituted with an alkoxy radical.
The abovementioned patent application only discloses the use, as anti-inflammatory agent, of a limited number of compounds formed of a sugar monomer.
Skin ageing is a physiological process involving environmental external factors and genetic factors. Extrinsic skin ageing results for example from chemical and physical environmental stimuli (exposure to sunlight, to UV radiation, stress, malnutrition), which damage the normal functions of the skin; intrinsic skin ageing results from a genetically programmed senescence.
The present invention relates to these two types of ageing.
A direct link has been shown between skin ageing and inflammation. Inflammation is a physiological response to any attack, for example chemical (UV, tobacco, pollution), mechanical or infectious attack, which results in the release of mediators of the prostaglandin (PGE2) or cytokine (Il-8) type. These proinflammatory mediators play a direct role in skin ageing, in particular by activation of proteases (elastases) involved in the formation of wrinkles, and of enzymes (metalloproteases) which degrade the components of the dermis and epidermis, in particular the extracellular matrix (Pillai et al., Int. J. Cosmet. Sci., 2005, 27, 17-34).
Skin ageing additionally manifests itself by gradual weakening of the skin which then no longer plays its role as a barrier against external attacks as effectively. It has also been shown that the cells of the skin of elderly subjects, which have been subjected to UV radiation, express pro-inflammatory prostaglandins, in particular PGE2, and cyclooxygenase-2, in a larger quantity compared to those of young subjects. The study suggests that the increased expression, in elderly subjects, of these inflammation markers could play an important role in photo-induced skin ageing (Seo et al., Mech Ageing Dev. 2003 (8-9):903-10).
Moreover, some people have a genetic predisposition which confers on them heightened skin sensitivity to environmental or chemical stimuli or to factors such as emotions, compared with the reaction observed for the same stimulus on a “normal” skin, without the skin of the predisposed persons exhibiting a pathological state as a result.
This hypersensitivity manifests itself by non-pathological inflammatory manifestations and a sensation of discomfort on the skin, and in particular by tinglings, blotches, chafing, formication or itching, sometimes accompanied by blotches. The skin type of these people is often called “sensitive skin” or “reactive skin”.
It is therefore essential to have available active agents which are suitable for combating non-pathological manifestations of inflammatory origin by acting effectively on certain inflammation mediators, and which are thus capable of slowing skin ageing, of calming sensitive skins, of combating skin sensitivity and reactions of discomfort, of having a soothing, anti-irritation and antipruritus effect.